Polylysine dendrimers

Like PAMAM dendrimers, polylysine dendrimers are largely characterised by amide bonds. They attracted interest as potential therapeutic agents for use in boron neutron capture therapy and in magnetic resonance imaging (MRI) (see Chapter 8), since dendritic polylysines apparently have a lower toxicity than their linear counterparts. The polylysine shown in Fig. 4.10 with a total of 80 terminal boron atoms in the carborane units and a dansyl group was designed specifically for boron neutron capture therapy [20]. 

Synthesis of these dendrimers is performed by condensation of the amino acid lysine, whose amino functions have previously been protected with tert-bu-tyloxycarbonyl groups (Boc), onto an (activated) L-lysine p-nitrophenyl ester. The resulting coupling product (Fig. 4.11) is then deprotected with trifluoroacetic acid and thus activated for renewed reaction. Iteration of the assembly and activation step ultimately led to a polylysine dendrimer with 1024 terminal butyloxycarbonyl groups [21]. 

Balzani and Vogtle et al. studied the complexation of neodymium(III) and other rare earth metal ions by a luminescent second-generation polylysine den- 

Hardly any purely aliphatic hydrocarbon dendrimers have hitherto been prepared (see also Section 6.2.3.3), probably owing to fundamental synthetic problems in the formation of unsymmetrical C-C bonds. The dendritic hydrocarbons described so far are nearly all made up of condensed or coupled arene or/ and multiply bonded components, which is easier to achieve synthetically. As a rule, such molecules are generally much more conformationally rigid than their aliphatic analogues made up of [CH2]n units. 

The synthetic route to supertriptycene (C104H62) based on repeated Diels-Alder reaction is depicted in Fig. 4.13. Remarkably, this molecule possesses a symmetrical arrangement of three relatively rigid niches for possible inclusion of guests and enormous thermostability (in a nitrogen atmosphere it does not decompose until 580°C) [23]. 

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Fig. 3i-iii. Dendrimer synthesis using branched building blocks i Denkewalter s polylysine dendrimers ii Newkome s polyamide dendrimers iii Frechet s aryl ether dendrimers... 

E. A. B. Kantchev, C.-C. Chang, and D.-K. Chang, Direct Fmoc/tert-Bu solid phase synthesis of octamannosyl polylysine dendrimer-peptide conjugates, Biopolymers, 84 (2006) 232-240. 

Balzani V, Ceroni P, Gestermann S et al (2000) Effect of protons and metal ions on the fluorescence properties of a polylysin dendrimer containing twenty four dansyl units. J Chem Soc Dalton Trans 3765-3771... 

Fig. 1.3 Polylysine dendrimer (according to Denkewalter et al.) the two peripheral lysine units are shown in green...

Fig. 8.29 Organic nanotubes by core removal from polylysine dendrimers (according to Zimmerman et al.)...

VicinelU, V, Ceroni, R, Maestri, M., etal. (2002) Luminescent lanthanide ions hosted in a fluorescent polylysin dendrimer. Antenna-Uke sensitization of visible and near-infrared emission. Journal of the American Chemical Society, 124, 6461. 

Florence, A.T. Sakthivel, T. Toth, I. Oral uptake and translocation of a polylysine dendrimer with a lipid surface. J. Control. Release 2000, 65, 253-259. 

An antiviral compound comprises a dendrimer such as a polyamidoamine or polylysine dendrimer having a number of terminal groups, in which at least one of the terminal groups has an anionic- or cationic-containing moiety bonded to it, particularly a sulphonic acid-containing, carboxylic acid-containing or trimethylammonium-containing moiety, etc. 

Kaminskas, L.M. Kelly, B.D. McLeod, V.M. Sbema, G. Owen, D.J. Boyd, B.J. Porter, C.J. Characterisation and tumour targeting of PEGylated polylysine dendrimers bearing doxorubicin via a pH labile linker. J. Control. Release 2011,152 (2), 241-248. 

Polyamidoamine (PAMAM) dendrimers Polypropylene Imlne (PPI) dendrimers Polyester dendrimers Polylysine dendrimers... 

Numerous polymer-nucleic acid composites have been investigated in animal studies. The polymer systems that are most used are variations of PEI, polylysine, dendrimers, and a few others. There are also systems that are from natural polymers such as chitosan and atelocollagen. Here, a single system is outlined to show how some of the issues illustrated above are translated from the level of transfections in cdls to the treatment of humans in the clinic (the following discussion is adapted from the presentation by Davis" ). 

Figure 22 Supramolecular chemistry of polylysine dendrimers as described by Hirst et aO ...

The quenching arises from energy and electron transfer between the excited dansyl groups and the Co(II) amine complexes. Similar results have been obtained for lanthanide metals coordinated to the interior of polylysine dendrimers containing dansyl groups on the periphery. 

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